Nicotine has been proposed to have a number of pharmacological effects. See, for example, Pullan et al., N. Engl. J. Med. 330:811 (1994). Certain of those effects may be related to effects upon neurotransmitter release. See for example, Sjak-shie et al., Brain Res. 624:295 (1993), where neuroprotective effects of nicotine are proposed. Release of acetylcholine and dopamine by neurons upon administration of nicotine has been reported by Rowell et al., J. Neurochem. 43:1593 (1984); Rapier et al., J. Neurochem. 50:1123 (1988); Sandor et al., Brain Res. 567:313 (1991) and Vizi, Br. J. Pharmacol. 47:765 (1973). Release of norepinephrine by neurons upon administration of nicotine has been reported by Hall et al., Biochem. Pharmacol. 21:1829 (1972). Release of serotonin by neurons upon administration of nicotine has been reported by Hery et al., Arch. Int. Pharmacodyn. Ther. 296:91 (1977). Release of glutamate by neurons upon administration of nicotine has been reported by Toth et al., Neurochem. Res. 17:265 (1992). Confirmatory reports and additional recent studies have included the modulation, in the central nervous system (CNS), of glutamate, nitric oxide, GABA, takykinins, cytokines and peptides (reviewed in Brioni et al., Adv. Pharmacol. 37:153 (1997)). In addition, nicotine reportedly potentiates the pharmacological behavior of certain pharmaceutical compositions used for the treatment of certain CNS disorders. See Sanberg et al., Pharmacol. Biochem. & Behavior 46:303 (1993); Harsing et al., J. Neurochem. 59:48 (1993) and Hughes, Proceedings from Intl. Symp. Nic. S40 (1994). Furthermore, various other beneficial pharmacological effects of nicotine have been proposed. See, for example, Decina et al., Biol. Psychiatry 28:502 (1990); Wagner et al., Pharmacopsychiatry 21:301 (1988); Pomerleau et al., Addictive Behaviors 9:265 (1984); Onaivi et al., Life Sci. 54(3):193 (1994); Tripathi et al., J. Pharmacol. Exp. Ther. 221:91 (1982) and Hamon, Trends in Pharmacol. Res. 15:36.
Various nicotinic compounds have been reported as being useful for treating a wide variety of conditions and disorders. See, for example, Williams et al., Drug News & Perspectives 7(4):205 (1994); Arneric et al., CNS Drug Rev. 1(1):1 (1995); Arneric et al., Exp. Opin. Invest. Drugs 5(1):79 (1996); Bencherif et al., J. Pharmacol. Exp. Ther. 279:1413 (1996); Lippiello et al., J. Pharmacol. Exp. Ther. 279:1422 (1996); Damaj et al., J. Pharmacol. Exp. Ther. 291:390 (1999); Chiari et al., Anesthesiology 91:1447 (1999); Lavand'homme and Eisenbach, Anesthesiology 91:1455 (1999); Holladay et al., J. Med. Chem. 40(28): 4169 (1997); Bannon et al., Science 279: 77 (1998); PCT WO 94/08992, PCT WO 96/31475, and U.S. Pat. Nos. 5,583,140 to Bencherif et al., 5,597,919 to Dull et al., 5,604,231 to Smith et al. and 5,852,041 to Cosford et al. Nicotinic compounds are particularly useful for treating a wide variety of CNS disorders. Indeed, a wide variety of nicotinic compounds have been reported to have therapeutic properties. See, for example, Bencherif and Schmitt, Current Drug Targets: CNS and Neurological Disorders 1(4): 349 (2002); Levin and Rezvani, Current Drug Targets: CNS and Neurological Disorders 1(4): 423 (2002); O'Neill et al., Current Drug Targets: CNS and Neurological Disorders 1(4): 399 (2002); U.S. Pat. Nos. 5,1871,166 to Kikuchi et al., 5,672,601 to Cignarella, PCT WO 99/21834 and PCT WO 97/40049, UK Patent Application GB 2295387 and European Patent Application 297,858.
Pain can be classified in various ways and can be characterized by a variety of geneses and etiologies (e.g., inflammatory pain, neuropathic pain, chronic pain). Current pain therapy is dominated by two classes of drugs, the non-steroidal anti-inflammatory drugs (NSAIDs) and the opioids, both of which have significant therapeutic liabilities. Various compounds which target nAChRs have been shown to be effective in treating one or more kinds of pain in animal models. See for instance, Damaj et al., J. Pharmacol. Exp. Ther. 291:390 (1999); Damaj et al., Neuropharmacology 39:2785-2791 (2000); Chiari et al., Anesthesiology 91:1447 (1999); Lavand'homme and Eisenbach, Anesthesiology 91:1455 (1999); Holladay et al., J. Med. Chem. 40(28): 4169 (1997); Bannon et al., Science 279: 77 (1998); and Bannon et al., J Pharmacol Exp Ther. 285:787-794 (1998). Depending on the etiology of the pain, both the α4β2 and the α7 nAChR subtypes (which are CNS nAChR subtypes) have been identified as targets for analgesia. It would be beneficial to provide, with a single pharmaceutical agent, relief from multiple kinds of pain. It would also be beneficial to provide such relief without the gastrointestinal liabilities of the NSAIDs or the abuse potential of the opioids.
CNS disorders are a type of neurological disorder. CNS disorders can be drug induced; can be attributed to genetic predisposition, infection or trauma; or can be of unknown etiology. CNS disorders comprise neuropsychiatric disorders, neurological diseases and mental illnesses; and include neurodegenerative diseases, behavioral disorders, cognitive disorders and cognitive affective disorders. There are several CNS disorders whose clinical manifestations have been attributed to CNS dysfunction (i.e., disorders resulting from inappropriate levels of neurotransmitter release, inappropriate properties of neurotransmitter receptors, and/or inappropriate interaction between neurotransmitters and neurotransmitter receptors). Several CNS disorders can be attributed to a deficiency of choline, dopamine, norepinephrine and/or serotonin. Relatively common CNS disorders include pre-senile dementia (early-onset Alzheimer's disease), senile dementia (dementia of the Alzheimer's type), micro-infarct dementia, AIDS-related dementia, Creutzfeld-Jakob disease, Pick's disease, Parkinsonism including Parkinson's disease, Lewy body dementia, progressive supranuclear palsy, Huntington's chorea, tardive dyskinesia, hyperkinesia, mania, attention deficit disorder, anxiety, dyslexia, schizophrenia, depression, obsessive-compulsive disorders, and Tourette's syndrome. Senile dementia of the Alzheimer's type (SDAT) is a debilitating neurodegenerative disease, mainly afflicting the elderly, characterized by a progressive intellectual and personality decline, as well as a loss of memory, perception, reasoning, orientation, and judgment. One feature of the disease is an observed decline in the function of cholinergic systems, and specifically, a severe depletion of cholinergic neurons (i.e., neurons that release acetylcholine, which is believed to be a neurotransmitter involved in learning and memory mechanisms). See, for example, Jones et al., Intern. J. Neurosci. 50:147 (1990); Perry, Br. Med. Bull. 42:63 (1986); and Sitaram et al., Science 201:274 (1978). It has been observed that nicotinic acetylcholine receptors, which bind nicotine and other nicotinic agonists with high affinity, are depleted during the progression of SDAT. See Giacobini, J. Neurosci. Res. 27:548 (1990) and Baron, Neurology 36:1490 (1986). As such, it would seem desirable to provide therapeutic compounds that either directly modulate (for example, that directly activate) nicotinic receptors in place of acetylcholine or act to minimize the loss of those nicotinic receptors.
Certain attempts have been made to treat SDAT. For example, nicotine has been suggested to possess an ability to activate nicotinic cholinergic receptors upon acute administration, and to elicit an increase in the number of such receptors upon chronic administration to animals. See, for example, Rowell, Adv. Behav. Biol. 31:191 (1987) and Marks, J. Pharmacol. Exp. Ther. 226:817 (1983). It also has been proposed that nicotine can act directly to elicit the release of acetylcholine in brain tissue, to improve cognitive functions, and to enhance attention. See Rowell et al., J. Neurochem. 43:1593 (1984); Sherwood, Human Psychopharm. 8:155 (1993); **HN: START HERE Hodges et al., Bio. of Nic. Edit. by Lippiello et al., p. 157 (1991); Sahakian et al., Br. J. Psych. 154:797 (1989); and U.S. Pat. Nos. 4,965,074 to Leeson and 5,242,935 to Lippiello et al. Other methods for treating SDAT have been proposed, including U.S. Pat. Nos. 5,212,188 to Caldwell et al. and 5,227,391 to Caldwell et al., European Patent Application No. 588,917 and PCT WO 96/30372. Another proposed treatment for SDAT is COGNEX®, which is a capsule containing tacrine hydrochloride, available from Parke-Davis Division of Warner-Lambert Company, which reportedly preserves existing acetylcholine levels in patients treated therewith.
Parkinson's disease (PD) is a debilitating neurodegenerative disease, presently of unknown etiology, characterized by tremors and muscular rigidity. A feature of the disease appears to involve the degeneration of dopaminergic neurons (i.e., which secrete dopamine). One symptom of the disease has been observed to be a concomitant loss of nicotinic receptors which are associated with such dopaminergic neurons, and which are believed to modulate the process of dopamine secretion. See Rinne et al., Brain Res. 54:167 (1991) and Clark et al., Br. J. Pharm. 85:827 (1985). It also has been proposed that nicotine can ameliorate the symptoms of PD, as discussed in Smith et al., Rev. Neurosci. 3(1):25 (1992).
Certain attempts have been made to treat PD. One proposed treatment for PD is SINEMET CR®, which is a sustained-release tablet containing a mixture of carbidopa and levodopa, available from The DuPont Merck Pharmaceutical Co. Another proposed treatment for PD is ELDEPRYL®, which is a tablet containing selegiline hydrochloride, available from Somerset Pharmaceuticals, Inc. Another proposed treatment for PD is PARLODEL®, which is a tablet containing bromocriptine mesylate, available from Sandoz Pharmaceuticals Corporation. Another method for treating PD and a variety of other neurodegenerative diseases has been proposed in U.S. Pat. No. 5,210,076 to Berliner et al.
Tourette's syndrome (TS) is an autosomal dominant neuropsychiatric disorder characterized by a range of neurological and behavioral symptoms. Typical symptoms include (i) the onset of the disorder before the age of 21 years, (ii) multiple motor and phonic tics although not necessarily concurrently, (iii) variance in the clinical phenomenology of the tics, and (iv) occurrence of quasi-daily tics throughout a period of time exceeding a year. Motor tics generally include eye blinking, head jerking, shoulder shrugging and facial grimacing; while phonic or vocal tics include throat clearing, sniffling, yelping, tongue clicking and uttering words out of context. The pathophysiology of TS presently is unknown, however it is believed that neurotransmission dysfunction is implicated with the disorder. For further discussion, see Calderon-Gonzalez et al., Intern. Pediat. 8(2):176 (1993) and Oxford Textbook of Medicine, Weatherall et al., eds., p. 218 (1987).
It has been proposed that nicotine pharmacology is beneficial in suppressing the symptoms associated with TS. See Devor et al., The Lancet 8670: 1046 (1989); Jarvik, Brit. J. of Addic. 86: 571 (1991); McConville et al., Am. J. Psychiatry 148(6): 793 (1991); Newhouse et al., Brit. J. Addic. 86: 521 (1991); McConville et al., Biol. Psychiatry 31: 832 (1992); and Sanberg et al., Proceedings from Intl. Symp. Nic. S39 (1994). It also has been proposed to treat TS using HALDOL®, which is haloperidol available from McNeil Pharmaceutical; CATAPRES®, which is clonidine available from Boehringer Ingelheim Pharmaceuticals, Inc., ORAP®, which is pimozide available from Gate Pharmaceuticals; PROLIXIN®, which is fluphenazine available from Apothecon Division of Bristol-Myers Squibb Co.; and KLONOPIN®, which is clonazepam available from Hoffmann-LaRoche Inc.
Attention deficit disorder (ADD) is a disorder that affects mainly children, although ADD can affect adolescents and adults. See Vinson, Arch. Fam. Med. 3(5): 445 (1994); Hechtman, J. Psychiatry Neurosci. 19(3): 193 (1994); Faraone et al., Biol. Psychiatry 35(6): 398 (1994) and Malone et al., J. Child Neurol. 9(2): 181 (1994). Subjects suffering from the disorder typically have difficulty concentrating, listening, learning and completing tasks; and are restless, fidgety, impulsive, and easily distracted. Attention deficit disorder with hyperactivity (ADHD) includes the symptoms of ADD as well as a high level of activity (e.g., restlessness and movement). Attempts to treat ADD have involved administration of DEXEDRINE®, which is a sustained release capsule containing dextroamphetamine sulfate, available from SmithKline Beecham Pharmaceuticals; RITALIN®, which is a tablet containing methylphenidate hydrochloride, available from Ciba Pharmaceutical Company; and CYLERT®, which is a tablet containing premoline, available from Abbott Laboratories. In addition, it has been reported that administration of nicotine to an individual improves that individual's selective and sustained attention. See Warburton et al., Cholinergic Control of Cognitive Resources, Europsychobiology, Mendlewicz et al., eds., p. 43 (1993) and Levin et al., Psychopharmacology 123:55 (1996).
Schizophrenia is characterized by psychotic symptoms including delusions, catatonic behavior, and prominent hallucinations, and ultimately results in a profound decline in the psychosocial affect of the subject suffering therefrom. Traditionally, schizophrenia has been treated with KLONOPIN®, which is available as a tablet containing clonezepam, available from Hoffmann-LaRoche Inc.; THORAZINE®, which is available as a tablet containing chlorpromazine, available from SmithKline Beecham Pharmaceuticals; and CLORAZIL®, which is a tablet containing clozapine, available from Sandoz Pharmaceuticals. Such neuroleptics are believed to be effective as a result of interaction with the dopaminergic pathways of the CNS. In addition, a dopaminergic dysfunction possessed by individuals suffering from schizophrenia has been proposed. See Lieberman et al., Schizophr. Bull. 19:371 (1993) and Glassman, Amer. J. Psychiatry 150:546 (1993). Nicotine has been proposed to be effective in modulating neurotransmitter dysfunction associated with schizophrenia. See Merriam et al., Psychiatr. Annals 23:171 (1993) and Adler et al., Biol. Psychiatry 32:607 (1992). See also Freedman et al., Proc. Natl. Acad. Sci. 94:587 (1997).
It would be desirable to provide a useful method for the prevention and treatment of a condition or disorder by administering a nicotinic compound to a patient susceptible to or suffering from such a condition or disorder. It would be highly beneficial to provide individuals suffering from certain disorders (e.g., CNS diseases) with interruption of the symptoms of those disorders by the administration of a pharmaceutical composition containing an active ingredient having nicotinic pharmacology which has a beneficial effect (e.g., upon the functioning of the CNS), but does not provide any significant associated side effects. It would be highly desirable to provide a pharmaceutical composition incorporating a compound that interacts with nicotinic receptors, such as those that have the potential to affect the functioning of the CNS, and methods of treatment using the compounds and compositions. The present invention provides such compounds, compositions, and methods.
There exist subtypes of nAChRs in both the central and peripheral nervous systems, but the distribution of subtypes is heterogeneous. For instance, the subtypes which are predominant in vertebrate brain are α4β2, α7, and α3β2, whereas those which predominate at the autonomic ganglia are α3β4 and those of neuromuscular junction are α1β1δγ and α1β1εε (see for instance Dwoskin et al., Exp. Opin. Ther. Patents 10: 1561 (2000) and Schmitt and Bencherif, Annual Reports in Med. Chem. 35: 41 (2000)). A limitation of some nicotinic compounds is that they elicit various undesirable pharmacological effects because of their interaction with nAChRs in peripheral tissues (for example, by stimulating muscle and ganglionic nAChR subtypes). It would be desirable to have compounds, compositions and methods for preventing and/or treating various conditions or disorders (e.g., CNS disorders), including alleviating the symptoms of these disorders, where the compounds exhibit nicotinic pharmacology with a beneficial effect on the CNS nAChRs (e.g., upon the functioning of the CNS), but without significant associated effects on the peripheral nAChRs (compounds specific for CNS nAChRs, without significant effects on cardiovascular and/or skeletal muscle receptor sites).
Dopamine release is believed to be associated with the physiological “reward” associated with consumption of these substances of addiction. Modulation of dopamine release has been proposed for use in treating addiction. Modulation of the α4β2 receptor is one way to modulate dopamine release, and may be at least part of the mechanism by which mecamylamine is effective at treating drug addiction. However, it may be desirable in some instances to modulate dopamine release without antagonizing α4β2 activity. Thus, the availability of a variety of ligands that bind with high affinity and selectivity for receptors other than α4β2, and that modulate dopamine release, are of interest.
A limitation of some nicotinic compounds is that they are associated with various undesirable side effects, for example, by stimulating muscle and ganglionic receptors. It would be desirable to have compounds, compositions and methods for treating and/or preventing central nervous system disorders, and treating and/or preventing drug addiction, promoting smoking cessation, and inhibiting obesity, where the compounds exhibit pharmacology with a beneficial effect (e.g., inhibition of dopamine secretion), but without significant associated side effects. The present invention provides such compounds, compositions and methods.